New Delhi, Oct. 7: A vaccine against a cancer-causing virus has protected women from precancerous changes in the uterine cervix, bolstering hopes for an effective vaccine against cervical cancer, scientists announced today.

The vaccine, named Gardasil and produced by Merck, is designed to protect women from the human papilloma virus (HPV), an organism that spreads through sexual intercourse and can trigger genetic changes in cervical cells to cause cancer.

The vaccine protected 100 per cent of women from precancerous and non-invasive cervical cancers, researchers said, presenting the findings of clinical trials spanning 13 countries. India did not participate in the trial.

Precancerous changes are changes in the cell that signal the possible onset of cancer.

Gardasil is designed to target two types of the virus, HPV-16 and HPV-18, that account for 70 per cent of cervical cancers. “These are the first pivotal data to show that vaccination with Gardasil reduced HPV-16 and HPV-18-related cervical pre-cancer and non-invasive cervical cancer,” said Laura Koutsky, a principal investigator at the University of Washington, Seattle.

Cervical cancer is India’s biggest killer cancer among women, claiming more than 60,000 lives each year. A senior Indian Council of Medical Research (ICMR) official said India is negotiating with Merck for clinical trials of Gardasil in the country.

“Access has been our concern. We’ve asked the company to make the vaccine available at an affordable price if it is shown to be successful through clinical trials in India,” ICMR director-general Nirmal Ganguly said.

The studies, presented today at a meeting of the Infectious Diseases Society of America, have shown that among 5,301 women who received the vaccine, not one developed precancerous changes.

However, among 5,258 women who received a placebo, or sham treatment, 21 developed precancerous lesions or non-invasive cervical cancer.

Scientists have long been trying to develop a vaccine against cervical cancer, which is difficult to diagnose early because of absence of symptoms. The only early detection technique is through regular pap smear tests.

Although tens of millions of men and women worldwide get infected with HPV each year, natural immunity helps most of them get rid of the virus. But when the virus does persist in some cases, it can cause genital warts, benign cervical changes as well as cervical cancer. About 500,000 cervical cancer cases are diagnosed in the world each year.

The ICMR has asked the Institute of Cytology and Preventive Oncology in Noida to prepare guidelines for clinical trials for the vaccine against cervical cancer.